Wireless Multiple Temperature Measuring System Based On DS18B20 And NRF9E5

This paper introduces the design thought and implementation procedure of the multiple short distance wireless measuring system of temperature based on the digital temperature sensor DS18B20 and the single chip radio transceiver nRF9E5.With embeded MCU 51 kernel of RF transceiver chip nRF9E5 as the core of the system,it adopts digital temperature sensor DS18B20,applies sensing technology,wireless receive and transmite technology and computer technology,implements the acquisition of multiple temperature data and transmittes them in short distance wirelessly.The wireless multple temperature measuring systems based on DS18B20 and nRF9E5 is formed by two major parts mainly:First part is the data acquisition of the system,with a radio transceiver nRF9E5 chip as the core, make up temperature acquisition network with many chips of temperature sensor,complete the acquisition of multiple temperature data and transmitte them wirelessly.Second part is the data receiver of the system,with a radio transceiver nRF9E5 chip,through interface module RS-232,achieve the wireless receiving,and uploading function of temperature data.The acquisition port of the temperature data has adopted the digital integrated single-bus made temperature sensor DS18B20 from Dallas semiconductor Company of U.S.A..With unique single-bus interface,it can connect several dozen digital sensors on a signal line,it is verb,simple to connect with the interface of the microprocessor,very suitable for the measurement of temperature distributedly,make circuit structural design and hardware expenses of this system greatly simplify.The output of DS18B20 is digital,overcoming the shortcomings of needing A/D converter and other complicated external circuit while the analog temperature sensor connected with microprocessor interface,and it only takes up a I/O port of the microprocessor,so,are especially suitable for the lacking system of microprocessor I/O port resources.DS18B20 has CRC check-up function,dependability is high.Because every DS18B20 have only one sequence number and be recorded in the ROM when manufactured from the factory,so CPU can be identifed with the simple communication protocol,thus save a large number of lead wire and logical circuit.The single chip radio transceiver nRF9E5 is adopted for temperature data wireless transmission which made from Nordic VLSI Company of Norway. Regard nRF905 chip as the core,nRF9E5 is integrated with RF receiving and transmission,enhancement 8051 kernel,4input 10bit ADC,SPI,PWM,all among in the single chip,few peripheral circuit,the high-frequency components are all integrated within the chip,performance is steady and couldD interfered by the external electromagnetic interfere.Compared with bluetooth,nRF9E5 have no complicated communication protocol,totally transparent to users,the same kind of product can free communication,all working parameter can set up finishing through the software.Integrated 51 enhanced kernels within nRF9E5,neednDdispose the MCU alone,has already simplified the design of circuit,improve systematic anti-interference ability, so,nRF9E5 is the low cost RF system chip with small volume,lower consumption,few external components.This paper introduces the working principle of temperature sensor and radio transceiver chip,then expounds the hardware circuit structure and the software designing of relevant functions of the system in detail.The system's framework is simpleness,the performance is good,and the data transmission speed is fast,and its functions can be expanded easily,so it's suitable for wireless measuring of temperature in many application regions.